Avoiding turbulence. RAL scientists and software engineers have been working with United Airlines to test a new system for identifying hazardous turbulence in clouds. Led by scientists John Williams, Larry Cornman, and Bob Sharman, the team has developed the NEXRAD Turbulence Detection Algorithm, an automated procedure for analyzing data from ground-based Doppler radars and zeroing in on regions of air that can jolt an aircraft. Software engineers Steve Carson, Jason Craig, Gary Blackburn, and Jaimi Yee implemented the NTDA demonstration system, which utilizes real-time data from 24 radars to produce a 3-D map of in-cloud turbulence over the Midwest and Northeast regions of the country every five minutes.

The resulting snapshot of turbulence is made available to airline meteorologists and dispatchers via a Web-based display, and customized maps of turbulence are generated and transmitted from NCAR to the cockpits of select flights. The maps are designed to increase pilots' situational awareness, giving them the information they need to steer away from hazardous areas or at least turn on fasten-seatbelt signs.

Pinpointing turbulence in clouds is difficult, partly because the turbulent areas may be small, evolve quickly, and occur outside the most intense parts of a storm. Many factors can contaminate the radar measurements, such as strong sunlight, nearby storms, or even swarms of insects flying near the radar dish. The NTDA reprocesses the radar data and removes such contamination, while also averaging a series of measurements to improve the reliability of its turbulence estimates.

The NTDA is just one of several turbulence initiatives in RAL funded by the Federal Aviation Administration. Others include automated aircraft measurement and reporting of en-route turbulence, and model-based turbulence forecasts. By 2011, John expects the entire aviation industry will be guided by a system covering the continental United States that will update comprehensive turbulence "nowcasts" for pilots and air traffic managers every 15 minutes.

NSDL award. The Macaulay Library, a Web-based project funded by NSDL, recently won an award in the Science and Engineering Visualization Challenge, an annual contest sponsored by NSF and the journal Science. The library took second place in the audio and video category.

The library, which is accessible to the public, is a digital archive that contains the world's largest collection of animal sounds, as well as an interactive map showing where the animals were recorded. It also includes videos of animal behavior. The collection is used for educational purposes as well as to help researchers identify and study different species.

Funding for the project was provided as part of an NSDL initiative to enhance online science libraries and other resources.
The library can be found here.

Upper atmosphere impacts. Weather events in Earth's lower atmosphere appear to have surprisingly direct impacts on the structure of the upper atmosphere. A team of researchers, including ASP director Maura Hagan (who is also a scientist in HAO), found that intense thunderstorm activity over South America, Africa, and Southeast Asia generates tides of air that rise in the atmosphere to reach the electrically charged region known as the ionosphere.

The finding may help forecasters better predict turbulence in the ionosphere. Such turbulence can disrupt radio transmissions and signals from Global Positioning System (GPS) satellites.

The researchers examined images of the ionosphere that were taken by a NASA satellite. They identified regions that were located over tropical rainforests where extensive thunderstorm activity occurred. Using NCAR's Global Scale Wave Model, the researchers produced computer simulations showing that tides that initiate in the troposphere were transporting energy to a lower region of the ionosphere known as the E-layer, about 62 to 75 miles (100 to 120 kilometers) above Earth. The energy was disrupting the plasma currents in the E-layer and altering nearby electric fields.

The research team, led by Thomas Immel of the University of California, Berkeley, published its findings in the August 11 issue of Geophysical Research Letters.